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Patented Nov. 29,1892

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C. E..SGRIBNER. TELEPHONE EXCHANGE SYSTEM.

No. 487,097. Patented Nov. 29, 1892.

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UNITED STATES PATENT OEEICE.

CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE VESTERN ELECTRIC COMPANY, OF SAME PLACE.

TELEPHONE-EXCHANGE SYSTEM.

SPECIFICATION forming part of Letters Patent No. 487,0'7, dated November 29, 1892. Application filed April 16, 1892. Serial No. 429,487. (No model.)

To a/ZZ whom it may concern:

Be it known that I, CHARLES E. SCRIBNER,

a citizen of the United States, residing at Chicago, in the county of Cook and State of Illi- 5 nois, have invented a certain new and useful Improvement in Telephone-Exchange Systems, (Case No. 299,) of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to switchboard systems for telephone-exchanges. Its object is to provide means whereby thesub-st-ations of a telephone-exchange system maybe divided I5 into several groups, all the members of each group being connected to a separate switchboard and each member of each group being enabled to obtain connection at one or the other of the switchboards with another mem- 2o ber of the same or of another group, respectively.

I-Ieretot'ore in some exchange systems a circuit-wire or a calling-wire has been provided, extending to and looping through a considerable number ofsub-stations,an attendant being stationed at the exchange, constantly listening at a telephone included in the calling-wire circuit to receive calls from any substation connected with that particular calling-wire. In addition to the calling-circuit each sub-station is provided with a line-circuit extending to the exchange, and connected to `a terminal socket or spring-jack switch upon a switchboard thereat, whereby the attendant operator, having received an order over the call-circuit,may establish connectionby means of connecting cordsand plugs between any two lines on the switchboard. Since the number of subscribers to whose wants one operator can attend is limited, a number ot operators have each been furnished with terminal spring-jacks of all of the lines extending to the exchange, all the terminal spring-jacks of one line being connected in multiple tothe line-circuit. The n umber of spring-jacks and the number of switchboards is thus, in large exchanges very large, and the exchange is correspondingly expensive and troublesome.

In my invention I have divided the sub-sta- 5o tions into several groups. Each member of each group is connected to the exchange by a line-circuit and with an answering springjack switch upon each of the boards and with a line-jack or terminal switch upon one of the switchboards. Two or more calling-circuits, corresponding to the number of groups, extend to and include every sub-station ot' the exchange. Each olf' these circuits terminates in a telephone-receiver or other magnetic indicating device at one of the switchboards. 6o

The sub-station is provided with apparatus whereby the subscriber may introduce his telephone set into any calling-circuit at pleasure, and may thus give his order to the listening operator at any switchboard. Should a subscriber desire connection with another sub-station of the exchange system, he first ascertains to which group the su b-station with which he desires connection belongs. Then connecting his telephone set to the calling- 7o circuit terminating at the particular switchboard at which the terminal socket or line spring-jack of the line desired is situated he gives his order to the listening operator thereat. The operator then inserts one loop-plug of a pair into the answering-jack of the callingline and the other loop-plug of the pair into the terminal jack of the line called for, whereby the two subscribers are placed in communication. Thus each sub-station may be con- 8o sidered as being connected to two separate exchangesbyseparate calling-wires,but havinga line-circuit connected with an answering-jack at each of the exchanges, whereby he is enabled to call up and be connected to any subscriber of either exchange. A great saving is thus effected in the size and expense of the exchange system over an equivalent multipleswitchboard system, in which each subscriber is provided with a terminal spring-jack upon 9o every section of switchboard and an answering-jack at one of the boards. When each of the groups comprises a large number ot' substations, the switchboard upon which the terminal or line jacks of that group are located may be of the multiple type, a number of line-jacks upon the different sections of a multiple switch board being connected to each line-circuit.

Since it is impossible for a few listening oo operators to attend to the wants of all the members of one group7 a considerable number of calling-circuits may be provided for a large exchange, each group of calling-circuits extending to a subordinate smaller group of slib-stations, the different calling-circuits terminating at telephone-receivers upon the different switchboards, as herein described, one circuit terminating at each section ot' multiple switchboard.

If desired, other signal-receiving apparatus or indicating device than the telephone-receiver may be employed at the sub-station in place of the receivers to receive calling-signals, in which case a suitable source of current may be provided at the sub-station to actuate the signal-receiving device at the exchange.

My invention is adapted to either metallic or grounded circuit systems. The line-circuits or the calling-circuits, or both, may be either grounded or metallic.

Myinvention is illustrated in the accompanying drawings.

In Figure 1 thereof I have shown six substations divided into two groups of three each, the members of each group being counected, as described, with an answering-jack upon each of two switchboards and with a line-jack upon one of the boards. Two call.- ing-circuits are shown extending to and including all of the substations, each of the calling-circuits terminating in a telephone at one of the switchboards. In Fig. 2 l have represented eight sub-stations divided into two major groups connected to two different multiple-switchboard systems, each line-circuit from a substation being connected to an answering-jack upon one section of each of the multiple-switchboard systems and to alinejack upon each section of one of the multipleswitchboard systems. Each of the major groups ot two is divided into subordinate groups of two each, each subordinate group being provided with a pair of calling-circuits, one of which terminates at one section of each of the multiple-switchboard systems.

Referring to Fig. 1, I will briefly describe the apparatus at the sub-station, that at station 2,500 at the left of the drawings being taken for example. The apparatus com prises a signal-bell a and a telephone receiver a and transmitter a2 in two separate branches from a conductor?) and a gravity-switch a3, connected to the other conductor b of the line loop-key c at sub-station 2,500 is connected with the calling-circuit g, which is similarly connected through the other loop-keys at the different sub-stations and to a telephone-receiver e at the switchboard f. A telephoneline circuit Zt h extends from the conductors b b to answering-jacks t" and t' upon the switchboards f f, respectively, and to alinejack Z2 upon the switchboard f. Similar line-circuits extend from the sub-stations 1 and 5,000 to similar answering-jacks Za lc and Z Z upon the switchboards f f, respectively, and to line-jacks 7a2 and Z2 upon the switchboard f. Line-circuits m, n, and 0 extend from the sub-stations 5,001, 7,250, and 10,000 to answering-jacks o o', n n', and m fm', respectively, upon the two switchboards f f and to line spring-jacks 02, fm2, and m2 upon the switchboard f. It will be noted that the exchange system is supposed in this instance to consist of ten thousand subscribers, which are divided into two groups of tive thousand each, each member of each group having an answering-jack upon each of the switchboards ff', the lines from 1 to 5,000, inclusive, however, having their line-terminals upon the switchboard f and the stations from 5,001 to 10,000, inclusive, having their line-terminals upon the switchboardf.

The operator at each of the boards is provided with connecting and signaling apparatus, which may be of the usual character. It may comprise a pair of loop-plugs whose like contact-pieces are connected together through flexible cords, calling-keys being included in the cord-circuit, arranged to disconnect both contact-pieces of one of the plugs from those of the other and to connect them to a callinggenerator to send signal-current to the substations. Such apparatus is shown at the board f, whereat the operator is provided with a pair of plugs p p', connected by flexible conductors and connected with calling-keys q q, adapted to connect the contact-pieces of either plug to the calling-generator 1.

I will now describe the operation ot' the system shown. Suppose that subscriber at station 2,500 desires to obtain connection with sub-station 5,000. He depresses the key c', thereby opening the calling-circuit g and looping Vhis telephone set a a2, the receiver having been removed from the switch-hook 01,3 into the calling-circuit g. He then gives his order to the operator, listening at receiver c' at board f. This operator then inserts one loopplug p2 of the pair at her board into the answering-jack t" of line from station 2,500 and the other loop-plug p3 into the line-jack Z2 of line to station 5,000 at her board. The two substations are thus looped together into a continuous metallic circuit, which may be readily traced over conductors Zt Zt to answering-jack t', thence through plug p? and the cord-circuit to plug p3, thence to line-jack Z2, and thence over line Z3 Z4 to sub-station 5,000. The operator then depresses the plunger of a calling-key included in circuit with the plug p3, connecting that plug to a calling-generator IOO ITO

' 4eme? `and sendinga calling-current tohsub-station moved his telephone from his switch-hook, the

subscribers at station 2,500 and 5,000 are in communication. The apparatus at board f is shown in the position of connecting the substations 2,500 and 5,000, as described. Suppose7 again, that subscriber at station 2,500 should desire to communicate with a subscriber of the other group-say sub-station 7,250. He would then depress the plunger of key c, connecting his telephone set into the calling-.circuit Cl and giving his order through the telephone e to the operator at switchboard f. This operator would then insert one connecting-plug p of a pair into the answering-jack of station 2,500 and the other plug zo p into the line-jack n2 of station 7,250, whereby the sub-stations 2,500 and 7,250 would be connected into a similar continuous loop-circuit. The sub-stations l and 10,000 are shown thus connected at the boardf.

In Fig. 2 are shown eight sub stations, being members of an exchange system of ten thousand subscribers, which are similarly divided into two groups of tive thousand each; but these groups are further subdivided into `groups of two thousand iive hundred each.

Four calling-circuits are provided, arranged in two pairs, both members of each pair extending to two stations of each large group, one calling-circuit terminating in a telephonereceiver at each section of switchboard. Thus the circuit s extends to and includes the sub-stations l, 2,500, 5,001, and 7,250 and lterminates at the section t of the switchboard u. The alternate of the circuits s that is, the circuit s-extends to the same sub-stations and terminates at the section t of the switchboard u. Similarly the circuit s2 terminates at the section t2 of the board u and its mate or alternate s3 terminates upon the section 253 of board u. The line-circuit from each sub-station extends to an answering-jack upon one section of each switchboard, as stated, and to a line-jack of each section of one switchboard. Thus, for example, the linecircuit o of station l extends to answeringjacks o' and U2 upon the sections t and t ot' switchboards u and u and also to line-jacks o3 o4 upon the sections t and t2 of switchboard u. The line-circuits from the other sub-stations are similarly arranged.

Suppose that subscriber at station l desires connection with sub-station 2,500. He would send his call-signal over the calling-circuit s. The order would be received by the operator at board t, who would insert one loop-plug of a pair in the answering-jack fu of the line c and the other plug of the pair into the linejack w at her section't of the switchboard u, thus connecting the two sub-stations over lines o w. If a subscriber at station 2,501 should desire to connect with subscriber at station 10,000, he would send his order over the calling-circuit s3 and the operator at section t3 of board u would receive the call and establish the desired connection.

Any of the well-known testing systems may be applied to the exchange system herein to enable the operator at one section ot' the multiple switchboard to determine whether the line is already in use at some other section of switchboard or not. The other connecting appliances and calling apparatus may be variously modified in accordance with the varying conditions. Such modifications will readily suggest themselves to those skilled in the art to which this invention pertains.

Having th us described my invention, I claim as new and desire to secure by Letters Patent- 1. The combination, with a telephone-line circuit extending to an exchange, connecting with two spring-jacks upon two switchboards thereat, ot' two calling-circuits, each including telephone apparatus at the sub-station and each terminating in a telephone-receiver at one of the switchboards, whereby the subscriber is enabled to call the attention of the operator at either switchboard to his line-circuit and to obtain connection thereto at either switchboard, substantially as described.

2. The combination, with a telephone substation, of a line-circuit extending to an exchange and connected with a spring-jack upon each of two or more switchboards, two or more calling-circuits extending from the sub-station to the exchange, each calling-circuit terminating in a telephone-receiver upon a different switchboard, and means at the substation for including a sub-station telephone apparatus in any calling-circuit, as desired, whereby a subscriber is enabled to call the attention of the operator at any switchboard to his line and to obtain connection therewith, substantially as described.

3. The combination, with a telephone substation, of a line-circuit extending therefrom to an exchange and connected to a spring-jack switch upon each otl several switchboards thereat, two or more calling-circuits extending from the sub-station to the exchange, each calling-circuit terminating at the exchange in an electro-magnetic indicator, and means at the sub-station for connecting a source of electricity in any particular one of lthe calling-circuits, whereby a subscriber is enabled to attract the attention ot' the operator at any switchboard to his line-circuit and the operator at any switchboard may establish connection therewith, substantiallj,7 as described.

4. The combination, with a telephone Substation, of a line-circuit extending therefrom to an exchange, connected at the exchange to a spring-jack upon each of several switchboards, several calling circuits extending -from the sub-station to the exchange, each calling-circuit including at the exchange an electro-magnetic indicator, and loop-keys at the sub-station, included in the calling-circuits, adapted to include a source of electricity in said calling-circuit when actuated, substantially asdescribed.

5. The combination, with a 'telephone sub.- station, of a line-circuit extending therefrom to an exchange, connected at the exchange to a spring-jack switch upon each of several sw'itc-hboards, and connected to a line-jack upon one of the switchboards, several cal-ling circuits, each including an electro-niagnetic indicator at a different switchboard, and meansl at the sub-station for including a source of electricity in any particular callingci'rcuit, whereby a subscriber may call the attention of any operator, any operator may answer, and a particular operator may establish connection with the line, substantially as described.

6. rlhe combinatiomwithseveraltelephone sub-stations, of line-circuits, one for each sub- Station, extending to an exchange and connected to a spring-jack upon each of several switchboards, several calling-circuits, each extending to several sub-stations and including an electro-magnetic. indicator at a different switchboard, and means at each sub-station for including a source of electricity in any oney of the callingcircuits extending thereto substantial-ly as described.

7. The combinatiornwith several telephone sub-stations, of line-circuits, one extending from each sub-station to an exchange and connected to an answering-j ack upon each of several switchboards thereat and to a line-jack at one of the boards,` the line-jacks being arranged in groupsupon the different switch.- boards, several calling circuits extending from the exchange to several of the sub-stations, one calling-circuit extending from each of the s-witchboards to each of the sub-stations, each calling-circuit including atelephone-receiver at its particular switchboard at theexchange, means at` the sub-station for telephoning over any of the calling-circuits,and pairs ot' connected loop-plugs at the exchange, whereby any subscriber of any group may communicate an order to the operator at any switchboard to obtain connection with a member of the same or any other group of subscribers, substantially as described.

8. The combination, with several telephone sub-stations, of line-circuits, one line-circuit for each sub-station, extendingtoanexchange and connected thereatwith an answerin g-jack upon each of several switchboards and with a line-jack upon a particularone of theswitchboards, several calling circuits extending from the exchangeto the sub-station, one call'- ing-circuitv for each switchboardextending to each of the sub-stations, each calling-,circuit including a` telephone-receiver at its particular switchboard, loop-keys at th-e sub-station of each 1-ine-circuit,.each adapted to,A connect the telephone apparatus of the sub-station in a particular calling-ci.rcuit,a signal-bell at the sub-station in the line-circuit, pairs of loopplu-gs at the exchange, one plug of each pair being arranged for.` insertion into an answering-jack of the line and the other plug of the pair-being adapted to be inserted tutto; a linejack of a line, and keys adapted toy include a source of calLing-current in the plug-circuit to signal to a station, substantially as described.

9. The combination, with several telephone sub-stations, of line-circuits, one for eachsnbstation, each extending to an exchange and connected to: an answering-jack upon one section of each of several multipleswitchboards andl to a line-jack uponl each section ofaparticular multiple switchboard, calling-circuits, one extending from each section of multiple switchboard to several sub-stations, one calling-circuit extending from eachy switchboard to each sub-station, calling-circuits of the different sections of oneswitchboard extending to different sub-stations, each calling-circuit including av telephone-receiver at its particular section of switchboard, means. at the sub'- station for including the telephoneapparatus thereof in any calling-circuit connected thereto, and means upon eachl section of switchboard at the exchange for establishing connection between any answering-jack atA its particular switchboard and any line-jack at the same switchboard, substantially as described. t

In witness whereof I hereunto subscribe my name this 10th day of March, A. D. 1892.

CHARLES E. SCRIBNER.

Witnesses M. J. TALLETT, GEORGE MCMAHON. 

